A123 20Ah Quebec Group buy(Canada) cells ARRIVED 24.57$/cell

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Thank you Docbass and agniusm. There are hundreds of people who read and get good info without the neg. comments and question marks. Keep it up. But we do need questions. Thanks again.
 
Doc, you have real cells. Wondering if you can confirm some measurements and give me two others?

Cell thickness 7.2mm
Cell width 161mm
Cell height, not counting tabs, 227mm

cell tabs 45mm wide x 26mm long

I need the tab spacing from the edge of the cell foil pack, and the spacing between the + and - tab.

Thanks DOC! ... sorry if I missed these tab spacing dimensions somewhere... I searched.
 
bigmoose said:
Doc, you have real cells. Wondering if you can confirm some measurements and give me two others?

Cell thickness 7.2mm
Cell width 161mm
Cell height, not counting tabs, 227mm

cell tabs 45mm wide x 26mm long

I need the tab spacing from the edge of the cell foil pack, and the spacing between the + and - tab.

Thanks DOC! ... sorry if I missed these tab spacing dimensions somewhere... I searched.
Click to expand...

Hello Bigmoose, Here is the cell measurement ( sometime you will see the caliper grip not at the perfect location, .. it's because i'm holding the picture camera, cell andcaliper at teh same time!.. :lol: and i can not keep the caliper exactly in the location i took the measurement with) but the measurement are good. :wink:

Doc
 

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Thank you Doc! Exactly what I needed before mine arrive. Thanks again for helping us out! :D
 
I ordered my A123 20ah's from Xin last Thursday morning....just got message from DHL that they are on my local delivery truck! Clearing off my bench....

Update, just arrived! All look good and at 3.28 volts.
 
I am considering these cells for my ebike that currently uses 14S Headway cells. I have a width constraint of 4 inches in the triangle compartment that house the cells. If I calculate 14 x 7.25 mm thick I get 3.99".
I have never uses pouch cells so I little idea of their physical properties.

Does any one know if these cells stacked in series require an insulating spacer? If so that would make 14 of them to wide to fit 4 inches.

If 14 cells are stacked do they compress at all under their own weight or can they be compressed some? If so how much?
 
We should verify the pouch construction. I have "heard" that the positive tab is separated from the foil by a teflon spacer, but that the pouch foil is connected to the negative tab. The pouch foil is allegedly covered with an insulating polymer.

It would be good to know FOR SURE the specifics of the pouch's inherent insulation.

FWIW I was planning on placing 0.010 inch fishpaper between my cells or after I check the temperature capability, might use overhead projector transparency film.
 
Hello Bigmoose, Here is the cell measurement
Click to expand...

Hey doc, all my cells are slightly thicker in the very center of the cell, beyond the reach of your calipers, so I think that number might be higher... The calipers I have that are large enough to reach the center of the cell are too crude to give an accurate measurement.

bigmoose said:
FWIW I was planning on placing 0.010 inch fishpaper between my cells or after I check the temperature capability, might use overhead projector transparency film.
Click to expand...

I used (3) sheets of newspaper as a seperator and wear barrier.
 
I would think something more fire retardant and that can withstand high temps would be better! Perhaps Teflon sheets? It comes in 1/32" sheets.

http://www.scicominc.com/index.php/products/teflonr-products/teflon-sheet-stock
 
Ypedal said:
newspaper ?..... :eek:
Click to expand...

Yep, I have several years of experience using this method. Here are two build threads detailing it:
2011: http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=29959#p432960
2010: http://endless-sphere.com/forums/viewtopic.php?f=6&t=12461&start=60#p281360

I had (3) objectives for this barrier:
1) Separate the cells to prevent microconductance
2) introduce a layer that would wear down from vibration, instead of the plastic coating on the cells
3) Maximize heat transfer.

I went through a variety of materials before settling on simple newspaper. One sheet on each cell, which lightly adheres to the plastic coating on the cell, and a third sheet to wear between them.

I would think something more fire retardant and that can withstand high temps would be better! Perhaps Teflon sheets? It comes in 1/32" sheets.
Click to expand...

If my pack exceeds 451 degrees - the ignition point of paper - I have a lot of other issues, like the heatshrink and insulation on my power wires melting off. Teflon would be offgassing deadly, dangerous gas at that temperature. I am sure there are a lot of sophisticated materials that would yield additional benefits, but newspaper met my objectives.
 
agniusm,
you did not mention how you, at what current you discharged?
Doc,
yes about CBAIII
it is subject to just basic electricity rules I understand very well, I use wires supplied by West Mountan Radio with matching plug which are compensated for as I was told.
I checked voltages, CBAIII displays close to 0.1V MORE during test than I can read on my Tektronix meter. So when CBAIII desplays 3.0V it is in reality only 2.9V for example. Which is reverse what you said.
 
miro13car said:
agniusm,
you did not mention how you, at what current you discharged?
Click to expand...
I discharged them at low current, i wasn't using external load, and iCharger 206b can dissipate 20W of heat, so thats around 5-6ams. I think you have to cycle discharge >5 times to get proper reading. I done just one cycle to match cell capacity for two projects, lower ones for scooter and rest for cargo bike. I bought 6 more cells through ONS power, it was a group buy back here in Lithuania, and fellow tested few returning >19AH capacity.

One cell i have went soft. Gel feel inside. It was wet when i find it with nasty smell. I dont know what happened, capacity did not change. Prob. i will throw in youtube to show.

EDIT:
[youtube]uX1d71klbag[/youtube]
 
Yup. It looks as if there's a hole in the pack easily visible at the 6 second mark in the video.

http://www.youtube.com/watch?v=uX1d71klbag&feature=player_detailpage#t=6s
 
How does the hole affect the performance/longevity of the cell?!? :shock:

If it damages it irreparably, then these will need to be babied!
 
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